<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>简易ATM机</title>
    <script>
        var yue = 100;
        while (1 <= 100) {
            var sum = prompt('请输入你要的操作： ' + '\n' + '1.存钱' + '\n' + '2.取钱' + '\n' + '3.显示余额' + '\n' + '4.退出'
            )
            if (sum == 1) {
                var sum11 = prompt('请输入要存的钱数：')
                var yue = yue + Number(sum11)
                alert('您的钱数是：' + yue)
            }
            else if (sum == 2) {
                var sum21 = prompt('请输入要取的钱数：')
                var yue = yue - Number(sum21)
                alert('您的钱数是：' + yue)
            }
            else if (sum == 3) {
                alert('您的余额为：' + yue)
            }
            else if (sum == 4) {
                break
            }
        }
    </script>
</head>

<body>

</body>

</html>